Bumping gaia.json for 2 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/a6811f969b1f
Author: Teodosia Pop <teodosia.pop@gmail.com>
Desc: Merge pull request #13830 from bebef1987/del_cont

Bug 938051 - Intermittent failure in test_delete_contact

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https://hg.mozilla.org/integration/gaia-1_2/rev/6ea068cda781
Author: Bebe <bebe@mozilla.ro>
Desc: Bug 938051 - Intermittent failure in test_delete_contact